In response to demands in the market, there have been proposed many technologies which allow a vehicle to urgently travel several hundreds kilometers when a pneumatic tire thereof is punctured during traveling. These many proposals include such a technology disclosed in, for example, Unexamined Japanese Patent Application Publication No. 10-297226 that a support member is mounted on a rim in the cavity of a pneumatic tire assembled on the rim, and supports the tire when punctured to thereby enable run-flat traveling.
The above run-flat support member comprises an annular shell having a support surface located radially outward and a leg structure in an open state disposed radially inward, and elastic rings attached to two leg portions of the leg structure, and is supported on the rim via the elastic rings. The run-flat support member allows existing wheels and rims to be used without any specific modifications, and can therefore be advantageously adopted without causing confusions in the market.
Recently, as part of environmental measures, low noise pneumatic tires has been required. Pneumatic tires cause resonance of the air in the cavity of the pneumatic tire during traveling, which is one of the causes that increase road noise.
Conventionally, to solve the above problem, in common tire/wheel assemblies having a wheel and a pneumatic tire mounted on the rim thereof, for example, Unexamined Japanese Patent Application Publication No. 2001-113902 discloses such a technology that protrusions are disposed on the rim at predetermined intervals in the tire circumferential direction to vary the cross-sectional area of the cavity surrounded by the rim and pneumatic tire in the tire circumferential direction, thereby varying the frequency of the air resonance to reduce road noise due to the air resonance.
However, there have not been proposed any effective noise reduction measures with respect to the tire/wheel assembly having the above-mentioned ran-flat support member, and proposals for improvement technologies are desired.